Recoilless rifle ammunition



Jan. 21, 1964 D. BENDERSKY RECOILLESS RIFLE AMMUNITION 6 Sheets-Sheet 1 Filed May 29, 1961 FIG.|.

FIG. 2A.

INVEN TOR. DAVID BENDERSKY 8Y1 W023i:

ATTORNEYS:

Jan. 21, 1964 D. BENDERSKY ,3

RECOILLESS RIFLE AMMUNITION Filed May 29. 1961 e Sheets-Sheet 2 FIG. 3.

IN VENTOR. DAVID BENDERSKY ATTORNEYS:

Jan. 21, 1964 D. BENDERSKY 3,118,376 I RECOILLESS RIFLE AMMUNITION Filed May 29. 1961 6 Sheets-Sheet 3 GREASE AND WITH LBS.

ITH l.

- IN V EN TOR. DAVID BENDERSK ATTORNEYS 1964 D. BENDERSKY 3,118,376

RECOILLESS RIFLE muumon Filed may 29. 1961 6 Sheets-Sheet 4 IN VEN TOR. DAVID BENDERSKY BY 1/ P015164 ATTORNEYS:

Jan. 21, 1964 D. BENDERSKY 3,118,376

RECOILLESS RIFLE AMMUNITION Filed May 29, 1961 G'Sheets-Sheet 5 INVENTOR. DAVID BEN DERSKY ATTORNEYS:

Jan. 21, 1964 D. BENDERSKY 3,118,376

RECOILLESS RIFLE AMMUNITION Filed May 29. 1961 6 Sheets-Sheet 6 INVENTOR. DAVID BENDERSKY ATTORNEYS:

United States Patent 3,118,376 RECOILLESS RIFLE AMMUNITION David Bendersky, Kansas City, Mo., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Army Filed May 29, 1961, Ser. No. 113,568 2 Claims. (Cl. 10238) This invention relates to recoilless rifle ammunition, and more especially to an improved round which is designed to be fired with less heating and erosion of the rifle wall than has been realized heretofore.

As the temperature of the material of a gun increases, its strength decreases. If the heat input to the gun material per round fired can be reduced, the operational and design characteristics of the gun can be improved. This result is achieved in connection with conventional weapons by means of a felt-like pad which is impregnated with a smear material, is located behind the projectile, and is separated from the charge by a cupped cardboard piston. Upon firing, the pad is compressed and smears the wall of the barrel as it travels ahead of the propellant gas. The layer of smear material thus deposited on the barrel surface acts as a barrier reducing both the heat transferred to the barrel and the erosion eflfects during a crucial part of the firing cycle.

The technique heretofore utilized in connection with conventional weapons is not applicable to the recoilless rifle for the reason that this rifle undergoes its highest temperature rise and erosion in the chamber area. The present invention overcomes this difficulty by the provision of an improved round which functions to apply the smear material to the gun wall by a new and more efiective method.

The invention will be better understood from the following description when considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

FIG. 1 illustrates the improved round, the cartridge case being shown in section,

FIG. 2 is a partial sectional view of the rifle utilized in testing the round,

FIG. 2A is a breech end view of the rifle of FIG. 2,

FIG. 3 indicates the temperature reduction elfected by different layers of silicone grease,

FIG. 4 indicates the temperature reducing elfect of petroleum grease,

FIG. 5 indicates the relation between internal surface temperature and grease thickness,

FIGS. 6 to 11 show the relation between temperature rise and time at different points along the chamber of the rifle and with different amounts of grease, and

FIG. 12 indicates the radial distribution of the heat at one station along the chamber of the rifle.

The round illustrated by FIG. 1 includes a casing 20, a projectile 21, an adapter 22, a boom 23 and fins 24. The casing 20 has a plurality of openings 25. The boom 23 is hollow, has a plurality of perforations 26 and contains an ignition powder which may be ignited by an electric primer or other suitable means.

Surrounding the boom 23 and extending between the adapter 22 and fins 24 is a cylinder 28 of celluloid or the like. The propellant 29 of the round or cartridge is enclosed between the boom 23 and the cylinder 28. In the annular space between the casing 20 and the cylinder 28 is a layer 30 of temperature reducing grease.

The rifle used in testing the cartridge of FIG. 1 is illustrated by FIGS. 2 and 2A. It includes a barrel 31, a chamber 32 and a breech 33, which forms, together with a liner 34, a plurality of venturi openings 35. Located along the chamber 32 are test stations 36, 37, 38 and 39 which are spaced from the muzzle by 125 inches, 123.5 inches, 119 inches and 114.5 inches, respectively.

The curves A and B of FIG. 3 show the internal surface temperature time relations recorded at the chamber station 36 (FIG. 2) with two different thicknesses of silicone grease. Curve C shows the same relation without the use of any grease. It can be seen that the internal surface temperature of the chamber is very considerably reduced by the application of a one sixteenth inch layer of silicone grease.

The curve C of FIG. 4 is similar to the curve C of FIG. 3 and the curves E, F and G show the internal surface ternperature-time relationships for different thicknesses of petroleum grease. It will be noted from the curves of FIGS. 3 and 4 that silicone grease produces a greater reduction in maximum temperature than petroleum grease.

FIG. 5 shows plots of maximum temperature rise vs. grease layer thickness for both types of grease based on average values of seventeen records. It is evident that the silicone greases produce a greater reduction in the maximum temperature than petroleum grease in the range of thicknesses applied, and that there is no difference between the DC-33 and the DC-44 silicone greases.

Ten rounds similar to that of FIG. 1 were tested, six with the case perforation coverings intact and four with these coverings removed. Internal surface temperaturetime records were taken with petroleum grease and at chamber stations 36, 37, 3'8 and 39 (FIG. 2). FIGS. 6, 7, 8 and 9 show the resulting internal surface temperaturetime relations at the four stations. Station 36, as can be seen from FIGS. 1 and 2, is located some distance to the rear of the grease bearing cylinder 28 (FIG. 1).

An additional ten rounds containing petroleum grease were tested. Three of these rounds contained 0.8 lb. grease each and three rounds contained 0.5 lb. each. Comparative internal surface-time relations are shown in FIGS. 10 and 11. The last four rounds fired also contained 0.5 lb. grease. Internal surface temperature-time histories were taken at chamber station 37 from three thermocouples spaced peripherally at As shown by FIG. 12, a fairly even radial temperature distribution was obtained.

Rounds containing 0.5 lb. grease were found to produce no objectionable smoke or afterourning. Chamber pressure-time histories and muzzle velocity appear to be unaffected by the presence of grease in the round fired. The appliction of grease to the chamber wall appears to provide an effective thermal barrier. Not only is the internal surface temperature reduced, but there is also a delay in the time of the initial temperature rise. These combined efl'ects represent a considerable reduction in the area under the internal surface temperature-time cure which is proportional to the total heat transferred to the wall of the chamber.

I claim:

1. A recoilless rifle round of ammunition comprising a projectile,

a perforated boom behind said projectile,

ignition powder within said boom,

a primer for firing said ignition powder,

a propellant behind said projectile and generally surrounding the boom,

a cylindrical celluloid spacer for containing said propellant,

an aperture casing around said spacer providing an annular space therearound,

guide vanes mounted on a rear portion of said boom,

said vanes contacting an inner surface of said apertured casing,

a silicone grease carried by said round for coating walls of a recoilless rifle chamber in which said round is fired, said silicone grease being disposed circumferentially around said celluloid spacer whereby upon ignition of said propellant, said silicone grease will be blown radially outwardly and through said apertured casing onto the walls of the gun chamber for reducing the temperature thereof.

2. The device of claim 1 further characterized by said silicone grease having a thickness of about 75 of an inch.

References Cited in the file of this patent UNITED STATES PATENTS Patten June 20, 1916 Woodford Oct. 29, 1929 Taylor et a1. May 5, 1953 Engelke Sept. 15, 1953 Stevenson Apr. 25, 1961 Schecter et a1. Aug. 1, 1961 FOREIGN PATENTS France May 25, 1961 

1. A RECOILLESS RIFLE ROUND OF AMMUNITION COMPRISING A PROJECTILE, A PERFORATED BOOM BEHIND SAID PROJECTILE, IGNITION POWDER WITHIN SAID BOOM, A PRIMER FOR FIRING SAID IGNITION POWDER, A PROPELLANT BEHIND SAID PROJECTILE AND GENERALLY SURROUNDING THE BOOM, A CYLINDRICAL CELLULOID SPACER FOR CONTAINING SAID PROPELLANT, AN APERTURE CASING AROUND SAID SPACER PROVIDING AN ANNULAR SPACE THEREAROUND, GUIDE VANES MOUNTED ON A REAR PORTION OF SAID BOOM, SAID VANES CONTACTING AN INNER SURFACE OF SAID APERTURED CASING, A SILICONE GREASE CARRIED BY SAID ROUND FOR COATING WALLS OF A RECOILLESS RIFLE CHAMBER IN WHICH SAID ROUND IS FIRED, SAID SILICONE GREASE BEING DISPOSED CIRCUMFERENTIALLY AROUND SAID CELLULOID SPACER WHEREBY UPON IGNITION OF SAID PROPELLANT, SAID SILICONE GREASE WILL BE BLOWN RADIALLY OUTWARDLY AND THROUGH SAID APERTURED CASING ONTO THE WALLS OF THE GUN CHAMBER FOR REDUCING THE TEMPERATURE THEREOF. 